In the past, control systems such as building automation systems have typically been proprietary single manufacturer solutions, or complex integrations of independent systems. There have been efforts in the industry to define standards so that such systems can be integrated more effectively, but no truly uniform approach has been made available.
The release of the BACnet/LonMark™ fieldbus communication standards for building automation systems have initiated a rethinking of building automation system architectures that is likely to revolutionize the control solution landscape. Traditional proprietary building automation architectures perform well, but they are expensive to design and install, cumbersome to reconfigure, and often require reams of software to integrate the stand-alone facility services. By contrast, in a distributed BACnet/LonMark fieldbus architecture, logic processing is encapsulated into autonomous multi-vendor modules that communicate among themselves through standard software to cooperatively solve a building control problem. However, in known building automation architectures, the external interface characteristics of devices that are added to the control system must be entered into the database representation of the device's external interface characteristics before the BAS can effectively control the new device.
Distributing control in this way is expected to minimize installation wiring, optimize control software, lower operating/maintenance costs, and simplify system expansion. In today's competitive global marketplace, users need the fieldbus's flexible, reusable and cost-effective building control solutions to respond quickly to changes in facility management services.
There have been advances in other areas of computing which have, however, not been applied in a satisfactory manner to the field of building automation systems. For example, computer systems standards have developed to simplify the cost and development requirements to program systems. Primary technologies include object-oriented software, the Java™ Virtual Machine (JVM) and Java-Beans™.
Object-oriented programming provides a new way to model real-world entities more directly as software building blocks that match the real world better than conventional programming mechanisms. This new software paradigm has an increasing impact on the software realm, in the same way the microprocessor has impacted hardware design and functionality.
In object-oriented programming, application programs are created from self-contained building block modules (objects). Rather than reinventing the wheel every time they create a new program, application engineers can borrow pre-written application modules from a library and simply plug them in. By using object libraries, developers can concentrate on linking appropriate objects together and writing any custom objects that their applications require. Custom objects, in turn, can be added to the library for future reuse.
Networking standards have also developed in an effort to simplify the cost and development requirements to integrate systems. Primary technologies developed in the building automation industry include American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) Building and Control Network (BACnet™), and the ECHELON LONTALK™ protocol (developed by Echelon Corporation of Palo Alto, Calif.).
Meanwhile, in the computer industry, there have been efforts to develop communications standards, although again, these standards have not been applied in any truly effective way to the specific problems of building automation. For example, the goal of the Internet/WWW/Java/CORBA standards is to provide the information the user wants, without taking into account what kind of program to use, what computer it runs on, or the format of the information.
Through a system of hypertext, users of the Web have been able to select and view information from all over the world. However, the basic Web lacks true interactivity—real-time, dynamic, and visual interaction between the user and application. Java brings this missing interactivity to the Web. With a Java-enabled Web browser, the user can encounter animation and interactive applications.
Efforts to implement real time control systems over the Internet have generally been unsuccessful, because of variability in packet transit times and the lack of guaranteed delivery over the Internet.
In conclusion, control systems have historically been based primarily on proprietary technologies of a single manufacturer. Although there have been efforts to standardize these architectures, they have achieved only limited success. The inventors believe that there is a need for a highly integrated standard in the field of control systems which integrates a Java-based common object model, specially adapted for use in building automation applications, and provides central control and monitoring using communications network standards such as the internet